In connection with the technical background, reference is made, for example to German Patent Publications DE 29 47 521 A1 and DE 34 44 586 A1.
In connection with the employment of air-cooled turbine blades, in particular in gas turbines, the cooling air supply via channels in the rotating disks which terminate in the disk grooves, has basically proven itself. In this manner it is also possible to supply cooling air to a second turbine disk arranged behind a first disk, in that a portion of the air flow reaching the disk grooves of the first disk is moved via these disk grooves toward the back, so to speak, into the space between the first and second co-rotating disk. To this end it is possible to provide appropriate passages in the so-called retainer plates, which axially secure the blades inserted into the disk grooves.
The conveyance of a sufficiently large cooling air flow into the respective disk groove can be problematical, in particular if a portion of this cooling air flow is also intended for cooling a downstream turbine disk. It is not possible to design the cross-section a of a cooling air channel terminating in the groove bottom of the disk groove to have any arbitrary size, since in this outlet area individual stress concentrations of the peripheral stress are superimposed on each other and can cause locally greatly increased stress levels, which is undesirable.